High-frequency apparatus for severing vitreous articles



1952 M. DESCARSIN 2,615,286

HIGH-FREQUENCY APPARATUS FOR SEVERING VITREOUS ARTICLES Filed Aug. 51, 1948 lnvwtovq Maurice Desgarsin, His A bg zg.

Patented Oct. 28, 1952 HIGH-FREQUENCY APPARATUS FOR SEVER- ING VITREOUS ARTICLES Maurice Descarsin, Paris, France, assignor to General Electric Company, a corporation of New York Application August 31, 1948, Serial No. 47,032

- In France September 16, 1947 9 Claims.

My invention relates to high frequency apparatus for cutting and severing vitreous articles, and more particularly'relates to high frequency apparatus for cutting glass and vitreous tubes.

Thepresent invention relates to improvements in apparatus of the type disclosed and claimed in my U. S. Patent No. 2,385,567, granted September 25, 1945, upon an application filed September 25, 1941.

In some operations employed for the severing or cutting of glass and vitreous articles, such as glass tubes or tubing of larger diameter, it is diflicult to bring about a uniform preheating of the line or cut or severance. Moreover, the dissipation and flow of heat away from the proposed line of severance is objectionable and constitutes a substantial disadvantage particularly when gas flames are used for the preheating operation, which feature renders the cutting operation inaccurate. In accordance with my invention I provide new and improved apparatus which obviates the prior art disadvantages of this regard. v I

It is an object of my invention to provide new and improved apparatus for cutting and severing glass and vitreous articles.

It isanother object of my invention to provide new and improved apparatus and machines for cutting glass and vitreous tubes by utilizing inductive preheating, and additional dielectric heating when desired.

Generally speaking, in accordance with my invention, the preheating of .vitreous tubing is accomplished primarily by the inductive heating of conductive cuttingdiscs, and the additional heating is accomplished primarily by the dielectric heating of the glass with the same discs serving as electric field concentrators along the line of cut or severance. The tubing is rotated vertically, or rotated about its principal or longitudinal axis, and there is provided a plurality of annularly spaced cutting discs, the axes of rotation of which are parallel or substantially parallel to the rotational axis of the tubing to be cut, and these cutting discs are biased into physical and frictional contact with thetubing so that as the tubing is rotated the discs are also rotated by virtue of the frictional engagement therebetween. An annular region of preheating is established by the points of contact between the discs and the tubing, the discs being heated by electromagnetic induction and a substantial part of the heat being supplied for the preheating operation from the discs to the tubing. I provide within the vicinity of the cutting discs, and preferably extending on both sides thereof, a coil which is energized by high frequency current, to establish a high frequency electromagnetic field which heats the discs inductively. The range of preheating current frequency may be that disclosed in my patent identified above.

I also provide an improved high frequency heating arrangement for supplying additional heat to the tubing, primarily through direct dielectric heating of the glass itself near the edges of the discs, and also, to a certain extent, by further heating of the discs as a result of the additional current flowing throughthem. This second or additional application of high frequency heating causes the actual cutting or severance of the tubing. .The frequency of this'second means is preferably higher than that of the means which supplied the, preheat (for example, see Patent 2,385,567) and this higher frequency means may be constructed so that the discs themselves cooperating with plates or electrodes connected to the high frequency circuit constitute condensers of such higher frequency circuit, and of course serve as satisfactory coupling means which effect a concentration of the electric field, at their edges, into the glass. In this manner, the discs perform not only the heating and cutting operation, but also serve as a ready coupling means I and as capacitative'elements of the high frequency oscillatory circuit;

For a better understanding of my invention reference may be had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims. Fig; I is an elementary planar thereof I have positioned a plurality of annularly spaced cutting discs 2-I inclusive, which are preferably constructed of a refractory metal or graphite. Fig. 2 is a cross sectional view of the elemental arrangement shown in Fig. 1 along the axis AB. The vitreous tube I may be rotated by any suitable mechanical arrangement, and I have chosen to illustrate this means as comprising a rotatable table 8 having an annular ridge or flange 9 on the upper surface thereof and a plurality of annularly spaced and spring-tensioned holding elements III and II which engage the tube I at the lower extremity thereof. As a means for supporting the table 8 I employ a vertical shaft I2 which is supported by a journal (not shown) and the entire assembly may be rotated by means of a motor I3 driving a pinion gear I4 which engages an annular gear 15 on the inside of a lower flange I6 extending from the table 8.

Discs 2-I, inclusive, are rotatable upon their vertical axes, and the axes of rotation thereof are parallel to the axis of rotation of the tube I. Each of the discs 2-1, inclusive, is rotatably supported by a spring-biased vertical supporting haft (of which shafts IIand I8 associated with discs 2 and 5, are representative) into engagement with the outside surface of the tube I.

As a means for supplying heat to the tube I and to the discs 2-1 inclusive, and to establish thereby a localized annular region of preheating of the tube I, I provide a coil I9 which is preferably concentric with the tube I and preferably extends above and below the discs in order to assure the proper electromagnetic heating by induction thereof. In other words, the coil I9, which is energized by a suitable circuit I911, I912, establishes an electromagnetic field within the region of all, or some, of the cutting discs which serve to localize the high-frequency field applied to the tube.

The amount of heat supplied by the coil I9 may be sufficient not only to preheat the tube I but also to actually cut and sever the tube .I in a well-defined plane established by the various points of contact between the discs 2-1, inclusive, and the tube I. However, as a further refinement, I may provide additional means for supplying additional heating efiects to expedite the cutting operation, or which may find particular application where it is necessary to cut glass parts or vitreous parts having a large diameter and consisting of thick glass. More particularly, I provide in conjunction with the discs 2-1, inclusive, a second high frequency source or means, preferably at a higher frequency than the current which energizes coil I9. This high frequency circuit is illustrated schematically as comprising inductances 20 and 2|, and capacitative reactances constituting with the inductances the elements of a tuned or oscillatory circuit. These capacitances also serve the function of coupling the oscillatory circuit to the discs 2-1, thereby performing a circuit-connecting function as well as the heating-transfer function. I provide a plurality of plates or electrodes 22 and 23 associated with pairs of cutting discs, such as discs 2 and 5, or preferably with physically adjacent cutting discs. In this manner the disc 2 and the plate 22 constitute one electrical coupling condenser, and the disc and the plate 23 constitute another coupling condenser; and the electrical capacitative reactances thereof constitute with the inductive reactances of inductances 20'and 2| a tuned or oscillatory circuit. It will be understood that the oscillatory circuit includes the electric field existing at the edges of discs 2 and 5, and that this field is particularly concentrated in the material of tubing I, along the line of cut or severance, by the thin periph eral edges of the discs. The actual circuit in this case may correspond to those illustrated in my U. S. Patent 2,385,567, it being clearly understood by those skilled in the art, that the illustrated circuit is merely schematic. It will also be understood that where the discs are made of a material such as carbon which has a substantial resistance, the very high frequency current flowing through the discs in the oscillatory circuit causes an additional heating of the discs, which is also imparted to the glass at the line of cut or severance by the frictional contacts established at those points.

The foregoing heating operations, namely, the preheating achieved by inductive heating of the discs,and the additional heating achieved by dielectric heating of the glass through the electric field concentrated at the inside edges of the discs, are complementary and provide a highly efficient and economical process. It is a well-known fact that the resistivity of most glasses decreases with rising temperature. Accordingly, when the preheating has occurred, the resistivity of the glass has decreased to a point where the dielectric losses occurring atthe very high frequency of the additional heating are high enough to insure an eificient transfer of energy.

It will of course be understood, however, that the cutting operation may be achieved with either one of these heating processes independently of the other. For instance, where it is desired to cut thin-walled tubing, it may be desirable to utilize only the inductive heating of the discs. Where it is desired to cut glass tubing of very high resistivity, the dielectric heating may be utilized alone. On the other hand, where it is desired to cut substantially thick-walled tubing in the most expeditious fashion, both the inductive preheating of the discs and the dielectric heating of the glass at the edge of the discs will be utilized.

It will be understood that upon rotation of the tube I by the table 8 and associated drive means, the discs 24 will also be rotated and that by virtue of the spring-biasing means the discs will be forced into physical engagement with the outside surface of the tube I. As the heating operation or operations are applied, it will be apparent that the discs will penetrat the body of the tube I and will eventually penetrate the wall thereof effecting a clean well-defined out.

It is to be further understood that, although in the above-described operation the lower-frequency heating means I9 may energize the discs primarily, my invention is not to be limited to such applications. In view of the above it will be readily apparent to those skilled in the art that the coil I9 and the field produced thereby, may heat the tube I by virtue of its dielectric losses and that this heating may supplement that which is effected by the conduction of heat through the discs to the tube I.

The preheating of the discs is an important feature which aids in obtaining a precise and well-defined cutting of the tube I. While rotating, the individual discs trace the preheating line orplane and when this region has attained the desired temperature in order that the dielectric losses within the glass are sufliciently high, the extra-high frequency is applied as described in my above-identified patent. The preheating of the glass or tube to be cut is localized along the line traced by the discs that are heated by induction due to the coil l9. When the additional very high frequency heating is utilized, the cutting is accomplished by means of the dielectric-loss effect. It can thus be accomplished by using the preheating discs as electrodes of condensers which are energized by the higherfrequency current, so that the heating, which is due to the transmission of heat by the discs which are inductively heated, may be combined with the heat which is due to the dielectric losses caused by the high frequency field concentrated by the same discs.

While certain specific embodiments have been shown and described, it will of course be understood that various modifications may be made without departing from the invention. The appended claims are therefore intended to cover any such modifications coming within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In apparatus for severing a tubular vitreous article, the combination comprising, a coil energized with high frequency current, a plurality of conductive cutting discs Within the region of the field produced by said coil and heated thereby, said discs being of a relatively high resistance material of the group consisting of a, high resistance refractory metal and graphite and having axes of rotation substantially parallel to the longitudinal axis of the tubular article, and means for biasing said discs into contact with said article at their peripheries in order to sever said article in a plane established by the points of contact of the discs with the article.

2. In apparatus for cutting a vitreous tube, the combination comprising means for producing a high frequency field, a plurality of annularly spaced rotatable cutting discs being of a relatively high resistance conductive material of the group consisting of a high resistance refractory metal and graphite and contacting the tube at their peripheries and heated by said means, and means for biasing said discs into frictional contact with said tube to sever it in a plane established by the points of contact.

3. In apparatus for severing a vitreous tube, the combination comprising a heating coil concentric with the longitudinal axis of the tube and energized with high frequency current, a plurality of annularly spaced cutting discs of relatively high resistance conductive material of the group consisting of a high resistance refractory metal and graphite and biased into contact with said tube at their peripheries and rotatable upon axes parallel to the longitudinal axis of said tube and heated inductively by said coil, means for rotating said tube about its longitudinal axis and to eifect thereby rotation of the discs due to the frictional contact between the tube and the discs, and means for providing additional heating to said discs by capacitive coupling of voltages thereto at a frequency higher than that of the current through said coil.

4. In apparatus for cutting a vitreous tube, the combination comprising a coil concentric with the tube and energized with high frequency current, a plurality of annularly spaced cutting discs of relatively high resistance conductive material of the group consisting of a high resistance refractory metal and graphite biased into contact at their peripheries with the tube and having axes l 5.: In apparatus for cutting a vitreous tube, the

combination comprising a coil concentric with the tube and energized with high frequency current, a plurality of annularly spaced cutting discs of relatively high resistance conductive material of the group consisting of a high resistance refractory metal and graphite and biased into contact at their peripheries with the tube and having axes rotation of which are parallel to the longitudinal axis of the tube, said discs being located in proximity to said coil for achieving heating through inductive coupling thereto, means for biasing the discsinto contact with the tube to establish a localized annular region of preheating, and means for rotating the tube and to effect thereby rotation of the discs due to the frictional contact between the discs and the tube.

6. In apparatus for cutting a vitreous tube, the combination comprising, means for rotating the tube about its longitudinal axis, a plurality of annularly spaced rotatable cutting discs of relatively high resistance conductive material of the group consisting of a high resistance refractory metal and graphite and biased into engagement with said tube, whereby rotational motion is imparted to said discs by virtue of frictional engagement with said tube, and high frequency energizing means coupled to said discs and comprising an oscillatory circuit including capacitative reactance constituted at least in part by said discs.

7. In apparatus for cutting a vitreous tube, the combination comprising, means for rotating the tube about its longitudinal axis, means for preheating said tube in a localized annular region, a plurality of annularly spaced rotatable discs of relatively high resistance conductive material of the group consisting of a high resistance refratory metal and graphite and spring-biased into engagement with said tube and rotatable by frictional engagement therebetween, and means for supplying high frequency heating current to said discs whereby dielectric heating of said tube is achieved in the regions of electric field concentrations at the points of contact between the tube and the discs for severing said tube.

8. In apparatus for cutting a vitreous tube, the combination comprising, means for rotating the tube about its longitudinal axis, a plurality of annularly spaced rotatable cutting discs of relatively high resistance conductive material of the group consisting of a high resistance refractory metal and graphite and biased into engagement with said tube, means for preheating said tube in a localized annular region in a plane established by the points of contact between said tube and said discs, and high-frequency energizing means coupled to said discs and comprising an oscillatory circuit including capacitative reactances constituted at least in part by said discs operating through the glass of said tube a a dielectric, thereby to heat said tube at the regions of electric field concentration at said points of contact.

9. Apparatus for severing a vitreous tube, comprising means for rotating said tube about its longitudinal axis, a plurality of annularly spaced rotatable cutting discs of high resistance conductive material of the group consisting of a high resistance refractory metal and graphite and biased into engagement with said tube, inductive heating means for raising the temperature of said discs in order to preheat said tube in a localized annular region in a plane established by the points of contact between said tube and said discs, and dielectric heating means for coupling high frequency energy to said discs and establishing regions of high electric field concentration. at said points of contact in order to sever said tube thereat.

MAURICE DESCARSIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Number Name Date 2,385,567 Descarsin Sept. 25, 1945 2,428,969 Guyer Oct. 14, 1947 2,445,063 Guyer July 13, 1948 

